Posterior facet syndrome – what is it?

In an interesting article by Deborah Pate, who’s not thick, called “Determining a Diagnosis of Facet Syndrome” she says about posterior facet syndrome:

…that it is difficult if not impossible to make the diagnosis of facet syndrome, because there are usually several contributing factors. Degenerative disc and facet disease are often part of the complex and are either the main disorder contributing to the symptoms or at least a major contributing factor.”

Now, she’s a radiology genius and so you can see where she’s coming from.  In radiology terms it’s going to be a bit tricky to see a facet syndrome, in the same way it might be difficult to see an acute ankle sprain/strain (not break!) on x-ray.  However, the reason why it is a syndrome and not a simple facet strain is just because it does involve other different tissues which may include disc, joint, soft tissue and nerves, most of which you are going to struggle to see on an x-ray.

And she rightly adds:

The diagnosis of facet syndrome is most often a clinical diagnosis

Later, however, she adds a telling line:

This disorder can simulate a disc lesion. More often than we would like to admit, it is misdiagnosed as a disc lesion.

And never has a truer word been said.  If I had a day off for every PFS that was diagnosed as a slipped disc I’d be Rip Van Winkle.

Rip Van Winkle

This is probably is due to the fact that with MR studies you can evaluate the disc easily, and therefore attribute all the symptoms to the disc lesion when the disc is very likely not to cause of the patient’s complaints.

She goes on to note that on x-ray:

It is noted that an increase in the sacral base angle (posteriority of the gravity line) and in increase in the lumbosacral disc angle are associated with an increased incidence of the facet syndrome in patients with lower back pain.

She adds:

There should be a better way of determining the true cause of a patient’s clinical complaints. There should also certainly be a phase of conservative treatment before performing aggressive procedures such as surgery.

This I suspect is true and sounds pretty sensible ; the more its bio-mechanical challenged the more likely it is to go wrong – so don’t let your daughter do ballet or gymnastics – I don’t.

Hypermobility and low-back pain

A good role model – I don’t think so.

Professor McGill, who is the world’s most renown lumbar spine specialist, gave me a tip on a short but great screen for PFS – if the patient can’t extend backwards is most probably because the facets are on fire and it’s PFS; if they can’t lean forward it’s because the disc is on fire.  Dead easy start point to your evaluation.  So don’t give a patient with PFS Mackenzie exercises as some physios seem to do!

Whare are you posterior facet joints?

The anatomy of the facet joint is interesting and tells us a lot about why it stings in the way it does.  The larger nerve bundles that enter the fibrous joint capsule come from a couple of sources: the Dorsal primary rami of cervical, thoracic and lumbar spinal nerves supply two successive articulations, one above and one below which makes sense when you look at the vertebral body.  This means that each joint has a ‘bisegmental’ innervation.

In the lumbar region a deep branch of the dorsal ramus loops under an accessory process and burrows up and in to supply the multifidus, semispinalis and rotatores muscles.  It then gives off a small nerve branch to the upper outside edge of the capsule of the joint at the level from which the nerve is derived.  Complex?  Just you wait.Facet joint

Another more lateral branch of the same dorsal ramus goes up and round the accessory process, supplies parts of the sacrospinalis muscle, then sends a branch to the articulation a segment above.  So, a single lumbar spinal nerve supplies an articulation near where it starts and another joint one vertebra up the spine.

So, the patient with a typical facet syndrome will usually complain of a sudden onset of unilateral or bilateral low-back pain with or without radicular pain, extending into the extremity.  The referred pain pattern will differ depending on which facets are the cause of the symptoms.  The pain generally increases with motion (particularly with extension as I’ve mentioned) and is relieved by rest as then they are no longer compressing or twisting the joint.

Facet pain, unlike disc pain, is not usually increased by coughing and sneezing.  Localized tenderness usually is found at the lumbosacral junction and a “spring test” of the individual facets often will reproduce the pain.  The “spring test” can be performed by palpating the facet joint and pressing down on the facet with deep pressure, then releasing quickly.

Posterior facet syndrome classification

There have been attempts to classify PFS into:

  1. Traumatic: due to injury to the facet joint and associated with inflammation to the joint capsule;
  1. Pathologic: due to degenerative arthrosis of the facet joint and generally associated with degenerative disc disease;
  1. Postural: due to biomechanical changes that place more stress upon the facets. The classic, so chronic occupational strain by sitting at work for ever and obesity.

So, if you are having some issues with your back then come and see us as we do know what we are talking about.

References

Stilwell D, Jr. The Nerve Supply of the Vertebral Column and its Associated Structures. Stanford University, Department of Anatomy, Stanford, CA.

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